oracle.javatools.parser.util
Class KeywordTable

java.lang.Object
  oracle.javatools.parser.util.KeywordTable

public final class KeywordTable

extends java.lang.Object

The KeywordTable utility class is a stripped down hash table implementation with a couple assumptions:

• It is used for mapping keyword keys ("public") to token constants (TK_PUBLIC).
• No synchronization is provided as the hash table is not modified once it has been populated.
• Table sizes are power of two as mod (%) operations are very expensive.

See Also:

Lexer

Constructor Summary

KeywordTable(int numKeywords)
Constructs a new empty KeywordTable for the given size (number of keywords.)

Method Summary

void	addKeyword(java.lang.String keyword, int token) Adds the given keywords/token pair to the keyword table.
static int	computeHash(char[] keyword) Utility routine to calculate the hash value of a string used for this keyword table.
static int	computeInsensitiveHash(char[] keyword) Utility routine to calculate the (case insensitive) hash value of a string used for this keyword table.
static int	computeInsensitivePartialHash(char nextChar, int lastHash) Utility routine to calculate the (case insensitive) hash value of a keyword character by character (from left to right).
static int	computePartialHash(char nextChar, int lastHash) Utility routine to calculate the hash value of a keyword character by character (from left to right).
int	lookupKeyword(ReadTextBuffer buffer, int startOffset, int endOffset, int precomputedHash) Lookup the given keyword marked by the given start and end offset in the ReadTextBuffer, and return the matching token value, or Lexer.TK_NOT_FOUND if there is no such keyword in the table.
void	setCaseSensitivity(boolean isCaseSensitive) Sets the case sensitivity of the table as indiciated by client.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

KeywordTable

public KeywordTable(int numKeywords)

Constructs a new empty KeywordTable for the given size (number of keywords.)

Parameters:

numKeywords - number of expected keywords in table

Method Detail

setCaseSensitivity

public void setCaseSensitivity(boolean isCaseSensitive)

Sets the case sensitivity of the table as indiciated by client.

Parameters:

isCaseSensitive - true to perform case-sensitive lookups

addKeyword

public void addKeyword(java.lang.String keyword,
                       int token)

Adds the given keywords/token pair to the keyword table.

Parameters:

keyword - the keyword to use as a key to the hash table

token - the token value to use as the value

lookupKeyword

public int lookupKeyword(ReadTextBuffer buffer,
                         int startOffset,
                         int endOffset,
                         int precomputedHash)

Lookup the given keyword marked by the given start and end offset in the ReadTextBuffer, and return the matching token value, or Lexer.TK_NOT_FOUND if there is no such keyword in the table.

Parameters:

buffer - the TextBuffer of the keyword to look up

startOffset - the starting offset of the keyword in the buffer

endOffset - the ending offset of the keyword in the buffer

Returns:

the token value corresponding to the keyword or Lexer.TK_NOT_FOUND if the keyword is not found.

computeHash

public static int computeHash(char[] keyword)

Utility routine to calculate the hash value of a string used for this keyword table.

Parameters:

keyword - the keyword to hash

Returns:

the hash value

computeInsensitiveHash

public static int computeInsensitiveHash(char[] keyword)

Utility routine to calculate the (case insensitive) hash value of a string used for this keyword table.

Parameters:

keyword - the keyword to hash

Returns:

the hash value

computePartialHash

public static int computePartialHash(char nextChar,
                                     int lastHash)

Utility routine to calculate the hash value of a keyword character by character (from left to right). This is useful so that as we are looking for the end of the identifier in the Lexer, we can be calculating the hash value as we go.

Parameters:

nextChar - the next character in the sequence

lastHash - the last last value computed

Returns:

the new partial hash value

computeInsensitivePartialHash

public static int computeInsensitivePartialHash(char nextChar,
                                                int lastHash)

Utility routine to calculate the (case insensitive) hash value of a keyword character by character (from left to right). This is useful so that as we are looking for the end of the identifier in the Lexer, we can be calculating the hash value as we go.

Parameters:

nextChar - the next character in the sequence

lastHash - the last last value computed

Returns:

the new partial hash value